I never used to use a leader, but regularly checked the last few yards and cut off any damaged bit, and to be honest, I've never had a problem with breakages.
However, recently I have started using them but I find one big snag. WEED, especially in the Solent. Without fail, it snags on the knot and I go through some anxious moments trying to clear it when (on the rare occasion!) I have a decent fish on.
So I guess I am not wholly convinced yet!
Re hook lengths, I now use flurocarbon from 10 to 30lbs then some cheap, but excellent, 50lb clear, then 100lb Suffix clear, and finally 250lb stuff for the big long boys
I've tried to simplify things over the years and that's as far as I can take it.
Interesting thread though!
Martyn